Select the option that expresses the given sentence in reported speech.
"I will teach you," said the old man to his grandson.

Explanation of the Correct Answer:
· The sentence is in direct speech.
· When changing to indirect speech, we apply backshifting since the reporting verb ("said") is in the past.
· "Will" changes to "would."
· The pronouns are also adjusted:
· "I" → "he" (referring to the old man)
· "you" → "him" (referring to the grandson)
· Thus, the correct answer is:
· "The old man told his grandson that he would teach him."
Other options:
· (a) "That he taught him" → Incorrect because "taught" changes the meaning to the past instead of a future intention.
· (b) "Told his grandson to teach him" → Incorrect because it reverses the speaker and listener.
· (c) "Said that he will teach you" → Incorrect because "will" should change to "would" in reported speech.
Thus, the correct answer is (d).